KR100772509B1 - Optical device having optical waveguide of organic Bragg grating sheet - Google Patents

Abstract

The present invention comprises a cladding layer formed on a substrate and an optical waveguide formed in the cladding layer. The optical waveguide includes a core layer and an organic Bragg grating plate having a refractive index greater than that of the core layer and capable of reflecting or transmitting light having a specific wavelength in a middle portion of the core layer. As a result, the light waveguide may be advanced with high reflectivity and low loss. In addition, the present invention provides a high performance variable wavelength filter by forming a column electrode on an optical waveguide, making a tapered optical waveguide, or making an organic Bragg grating having chirp in the center of the core layer of the optical waveguide. Variable dispersion compensators can be implemented.

Description

Optical device having optical waveguide of organic Bragg grating sheet

1 is a cross-sectional view showing an optical device having an optical waveguide type organic Bragg grating plate according to the present invention.

2 and 3 are enlarged perspective views illustrating the organic Bragg grating plate of FIG. 1.

4 is a conventional optical device in which an organic Bragg grating plate is formed on the surface of an optical waveguide for comparison with the present invention.

5 and 6 are schematic cross-sectional views of the conventional optical device of FIG. 4 and the optical device of the present invention of FIG.

7 and 8 illustrate intensity profiles of optical modes of the optical devices of FIGS. 5 and 6, respectively.

9 is a cross-sectional view illustrating a variable wavelength filter or a variable dispersion compensator in which a column electrode is formed on an optical waveguide having an organic Bragg grating plate as an example of an optical device according to the present invention.

10 to 13 are enlarged cross-sectional views illustrating a variable wavelength filter or a variable dispersion compensator in which a column electrode is formed on an optical waveguide having an organic Bragg grating plate having the same period as various applications of the optical device according to the present invention.

14 to 17 are enlarged cross-sectional views illustrating a variable wavelength filter or a variable dispersion compensator in which a column electrode is formed on an optical waveguide having a chirped organic Bragg grating plate of which periods vary as various applications of the optical device according to the present invention.

The present invention relates to an optical device, and more particularly, to an optical device having a waveguide Bragg grating sheet using an organic material.

In general, conventional techniques for fabricating organic Bragg gratings in optical devices include replication, molding, embossing, stamping, e-beam writing, and lithography. Various techniques have been used, such as lithography and photochemical processing. The first six methods were mostly used to produce surface relief gratings. The photochemical process was then used to produce surface relief gratings or volume index gratings.

Representative examples of the organic surface embossed grating and the application of this, an optical waveguide type polymer Bragg grating wavelength filter was fabricated by integrating a high refractive index resol grating on a low loss polymer optical waveguide core layer (Min-Cheol Oh et al., Polymeric wavelength filters). with polymer grating, Applied Physics Letters, Vol. 72 No. 13, 1559 (1998)). In addition, variable wavelength filters were implemented using thermoelectrodes and thermo-optic effects (Min-Cheol Oh et al., Tunable wavelength filters with Bragg gratings in polymer waveguides, Applied Physics Letters, Vol. 73 No. 18, 2543 (1998) ). The high refractive index resol grating was manufactured by a phase mask and a photolithography method.

Typical organic volumetric index gratings and their applications include Bragg gratings inscribed using planar waveguide polymer optical waveguides using two-beam interference and the photolocking of an allied signal optical polymer. It was applied to optical devices such as multichannel optical Add / Drop multiplexer (OADM) (Louay Eldada et al., Integrated Multichannel OADMs Using Polymer Bragg Grating MZIs, IEEE Photonics Technology Letters, Vol. .10 No. 10, 1416 (1998), Louay Eldada et al., Thermooptic Planar Polymer Bragg Grating OADMs with Broad Tuning Range, IEEE Photonics Technology Letters, Vol. 11 No. 4, 448 (1999).

Accordingly, an aspect of the present invention relates to an optical device having an optical waveguide including a Bragg grating sheet having a larger refractive index than a core layer material near a core layer.

In order to achieve the above technical problem, an optical device according to an embodiment of the present invention comprises a cladding layer formed on a substrate, and an optical waveguide formed in the cladding layer. The optical waveguide includes a core layer and an organic Bragg grating plate having a refractive index greater than that of the core layer and capable of reflecting or transmitting light having a specific wavelength in the core layer.

The core layer may include a lower core layer and an upper core layer, and the organic Bragg grating may be positioned between the upper core layer and the lower core layer. It is preferable that the thickness of the said organic Bragg grating board is 1/2 or less of the thickness of the core layer whole. The organic Bragg grating plate may be made of a residual layer and a rod or stick-shaped rod of a predetermined period on the residual layer. The thickness of the residual layer may be greater than zero and less than or equal to the thickness of the organic Bragg grating.

In addition, an optical device according to another embodiment of the present invention comprises a cladding layer formed on a substrate and an optical waveguide formed in the cladding layer, wherein the optical waveguide is a lower core layer, an upper core layer, and the upper core layer and the lower core. Including the organic Bragg grating plate having a refractive index greater than the upper and lower core layer between the layers and capable of reflecting or transmitting light of a specific wavelength, and having a column electrode formed on the optical waveguide, the variable wavelength filter and variable dispersion Can be used as a compensator.

The optical waveguide may be a tapered optical waveguide whose width or thickness varies along the optical axis. The organic Bragg grating may be a tapered organic Bragg grating having a width or thickness varying along the optical axis. The column electrode may be a tapered column electrode whose width or thickness varies along the optical axis. The organic Bragg grating may be an organic Bragg grating having a constant bar cycle along the optical axis. The organic Bragg grating may be a lattice-shaped organic Bragg grating whose bar cycle is varied along the optical axis.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments of the present invention illustrated in the following may be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below, but may be implemented in various different forms. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. In the drawings, the size or thickness of films or regions is exaggerated for clarity.

1 is a cross-sectional view showing an optical device having an optical waveguide type organic Bragg grating plate according to the present invention.

Specifically, in the optical device according to the present invention, a cladding layer 12 is formed on a substrate 10, and a planar waveguide type optical waveguide 18 is formed in a central portion of the cladding layer 12. The optical waveguide 18 is an organic core waveguide. Near the central surface of the optical waveguide 18, a very thin organic Bragg grating plate 16 is introduced, having a larger refractive index than the material of the core layer 14.

The core layer 14 is composed of a lower core layer 14a and an upper core layer 14b. The organic Bragg grating 16 is located between the lower core layer 14a and the upper core layer 14b. The total thickness of the organic Bragg grating plate 16 is configured to be 1/2 or less of the total thickness of the core layer 14. In addition, although the optical waveguide 18 has a cross-sectional shape in a square shape, that is, a channel shape in FIG. 1, a stepped square shape, that is, a ridge waveguide, may also be configured.

In the optical waveguide (core waveguide) 18, since the cladding layer 12 having a small refractive index is formed around the core layer 14 having a large refractive index, light propagates through the core layer 14 by total reflection. The optical waveguide 18 including the organic Bragg grating plate 16 effectively reflects or transmits light of a specific wavelength.

2 and 3 are enlarged perspective views illustrating the organic Bragg grating plate of FIG. 1.

Specifically, FIGS. 2 and 3 are two types of organic Bragg gratings 16 introduced near the center plane of the optical waveguide 18. FIG. 2 is an organic Bragg grating 16 having rods 22 of constant period P1 on a residue layer 20. That is, the organic Bragg grating 16 of Fig. 2 has a bar 22 of a shape in which all cycles are constant P1. FIG. 3 is an organic Bragg grating 16 having a chirped rod 24 with a gradual change in period on the residual layer 20. The organic Bragg grating 16 of FIG. 3 has a period P1. It has a stick-shaped rod 24 gradually changing from P2 to Pn.

2 and 3, the residual layer 20 appears when fabricating the organic Bragg grating plate 16 by a method such as an imprint. In order to effectively control the effective refractive index, the residual layer 20 may be adjusted or removed by etching or the like. The total thickness of the organic Bragg grating plate 16 including the residual layer 20 is composed of 1/2 or less of the total thickness of the core layer 14. The residual layer 20 has a thickness greater than zero and less than or equal to the thickness of the organic Bragg grating 16.

4 is a conventional optical device in which an organic Bragg grating plate is formed on the surface of an optical waveguide for comparison with the present invention.

Specifically, in Fig. 4, the same reference numerals as in Fig. 1 denote the same members for convenience. 4 shows an organic Bragg grating plate 16 formed on the surface of the optical waveguide 18, that is, the top surface of the core layer 14, for comparison with the present invention.

5 and 6 are schematic cross-sectional views of the conventional optical device of FIG. 4 and the optical device of the present invention of FIG. In Figs. 5 and 6, the same reference numerals as in Figs. 1 and 4 denote the same members.

Specifically, FIGS. 5 and 6 are optical devices for experimenting with light propagation characteristics of a Transverse Magnetic (TM) basic mode having a wavelength of 1550 nm in the optical waveguide 18 having the Bragg grating plate 16. 5 is an organic Bragg grating plate formed on the core layer constituting the optical waveguide as a conventional optical device, Figure 6 is an organic Bragg grating plate is formed in the middle of the core layer constituting the optical waveguide as the optical device of the present invention. .

5 and 6, the refractive index nSi of the substrate 10 is 3.48, the refractive index of the cladding layer 12 is 1.43, the refractive index of the core layer 14 is 1.45, and the refractive index of the organic Bragg grating plate 16. Was 1.52. The thickness d of the board | substrate 10 is 30 micrometers, and the longitudinal length L2 and the horizontal length L3 of the optical waveguide 18 are comprised by 7 micrometers, and the cross-sectional area of the optical waveguide 18 is 49 micrometer <^2> . The lower surface of the optical waveguide 18 and the cladding layer 12, that is, the distance (L1, or thickness) between the surface of the substrate 10 is 13 占 퐉, and the distance between the optical waveguide 18 and the upper surface of the cladding layer 12 ( L 4, or thickness) was 13 μm, and the thickness of the organic breadboard 16 was 0.375 μm.

7 and 8 illustrate intensity profiles of optical modes of the optical devices of FIGS. 5 and 6, respectively.

Specifically, FIGS. 7 and 8 illustrate the optical intensity profile of the TM basic mode when light having a wavelength of 1550 nm passes through the optical waveguide having a length of 1 mm in the conventional optical device of FIG. 5 and the optical device of the present invention of FIG. 6, respectively. to be. In Figures 7 and 8, the X axis represents the horizontal direction length, and the Y axis represents the vertical direction length.

As shown in Fig. 7, the conventional optical element has the optical basic mode biased to one side. On the contrary, in the optical device of the present invention, the light basic mode is well confined to the core layer so that the light is constrained to the core layer. Therefore, it can be seen that the light which has traveled the optical waveguide having the organic Bragg grating plate formed in the middle of the core layer like the optical device of the present invention not only obtains Bragg wavelength reflectivity of high efficiency but also is very small in terms of loss of light.

Hereinafter, an application example using the optical device of FIG. 1 will be described. According to the present invention, in order to control an effective refractive index according to a wavelength of an optical waveguide including an organic Bragg grating plate, a predetermined thermal electrode is formed on the optical waveguide, a tapered optical waveguide, or a core layer of the optical waveguide. You can make an organic Bragg grating with a chirp in the center. Accordingly, the optical device of the present invention may be manufactured as a tunable wavelength filter for adjusting the reflected wavelength or the wavelength bandwidth or a tunable dispersion compensator for adjusting the color dispersion of the optical signal.

9 is a cross-sectional view illustrating a variable wavelength filter or a variable dispersion compensator in which a column electrode is formed on an optical waveguide having an organic Bragg grating plate as an application example of an optical device according to the present invention.

Specifically, the same reference numerals as in FIG. 1 denote the same members. As shown in FIG. 9, a column electrode 26 is formed on the optical waveguide 18 having the organic Bragg grating plate 16 formed in the middle portion of the core layer 14, so that the variable wavelength filter or the variable dispersion compensator is formed by the thermo-optic effect. Is an implementation. In other words, FIG. 9 illustrates a variable wavelength filter or optical signal in which the column electrode 26 formed on the optical waveguide 18 can change the wavelength by changing the effective refractive index of the optical waveguide 18 by a thermo-optic effect. It implements a variable dispersion compensator that controls the amount of color dispersion.

10 to 13 are enlarged cross-sectional views illustrating a variable wavelength filter or a variable dispersion compensator in which a column electrode is formed on an optical waveguide having an organic Bragg grating plate having the same period as various applications of the optical device according to the present invention.

Specifically, in Figs. 10 to 13, the same reference numerals as in Figs. 1 and 9 denote the same members. 10 to 13, the column electrodes 26 and 26a are shown schematically, and may be formed anywhere as long as they are formed above and below the optical waveguide 18.

FIG. 10 illustrates a variable wavelength filter or a variable dispersion compensator having the structure shown in FIG. 9. That is, FIG. 10 illustrates an optical waveguide 18 having an organic Bragg grating plate 16 and a column electrode 26 disposed above and below the optical waveguide to implement a variable wavelength filter or a variable dispersion compensator by thermo-optic effects. It is.

FIG. 11 illustrates a variable wavelength filter or variable dispersion compensator having tapered optical waveguides 18a and tapered Bragg gratings 16a that vary in width or thickness along the optical axis. The tapered optical waveguide 18a and the tapered organic Bragg grating 16a are made by etching the optical waveguide 18 including the organic Bragg grating 16 in the formation of the optical waveguide 18. Accordingly, shown in FIG. 11 is a variable wavelength filter or variable dispersion compensator that adjusts the amount of chromatic dispersion according to the wavelength by varying the effective refractive index gradually along the axis of the optical waveguide 18a to increase the bandwidth of the Bragg reflected wave.

12 is the same variable wavelength filter or variable dispersion compensator except having a tapered column electrode 26a that varies in width or thickness along the optical axis as compared to FIG. The tapered column electrode 26a gradually changes the width or thickness of the column electrode when the column electrode 26 is formed. Accordingly, FIG. 12 illustrates a variable wavelength filter or variable dispersion compensator in which the resistance gradually changes along the optical waveguide 18 to gradually change the effective refractive index by the thermo-optic effect.

FIG. 13 is a combination structure of FIGS. 11 and 12, wherein a variable wavelength filter or variable dispersion compensator having a tapered optical waveguide 18a, a tapered Bragg grating 16a, and a tapered column electrode 26a is shown. It is shown.

14 to 17 are enlarged cross-sectional views illustrating a variable wavelength filter or a variable dispersion compensator in which a column electrode is formed on an optical waveguide having a chirped organic Bragg grating plate of which periods vary as various applications of the optical device according to the present invention.

Specifically, in Figs. 14 to 17, the same reference numerals as Figs. 1 and 9, and Figs. 10 to 13 denote the same members. 14 to 17, the column electrodes 26 and 26a are schematically shown and may be formed anywhere as long as they are formed above and below the optical waveguide 18.

FIG. 14 shows the same variable wavelength filter or variable dispersion compensator except having a chirped organic Bragg grating 16b whose period changes gradually compared to FIG. 10. The tacked organic Bragg grating 16b is made when the Bragg grating 16 is formed. FIG. 15 illustrates a variable wavelength filter or variable dispersion compensator using a structure of a patched and tapered organic Bragg grating 16c and a tapered optical waveguide 18a. FIG. 15 illustrates a variable wavelength filter or a variable dispersion compensator implemented using the structures of FIGS. 14 and 11.

FIG. 16 illustrates a variable wavelength filter or a variable dispersion compensator using the structure of a patch-shaped Bragg grating 16b and a tapered column electrode 26a whose periods change gradually. FIG. 16 illustrates a variable wavelength filter and a variable dispersion compensator implemented using the structures of FIGS. 14 and 12. .

FIG. 17 illustrates a variable wavelength filter or variable dispersion compensator using the structure of a sharp, tapered organic Bragg grating 16c, a tapered optical waveguide 18a, and a tapered column electrode 26a whose periods change gradually. . FIG. 17 illustrates a variable wavelength filter and a variable dispersion compensator implemented using the structures of FIGS. 15 and 13.

10 to 17, a variable wavelength filter and a variable dispersion compensator having various structures are shown as an application of the optical device of the present invention. If necessary, the optical waveguide 18 is a tapered optical waveguide 18a of varying in width or thickness along the optical axis, and the organic Bragg grating 16 is of tapered organic Bragg grating in which the width or thickness is changed along the optical axis ( 16a), the column electrode 26 has a tapered column electrode 26a of varying in width or thickness along the optical axis, and the organic Bragg grating plate 16 has an organic Bragg grating plate 16 having a constant cycle along the optical axis (or the The organic Bragg grating 16 may implement a variable wavelength filter and a variable dispersion compensator by combining the chirped organic Bragg grating 16b whose period varies along the optical axis.

18 and 19 are sectional views showing the optical device forming method according to the present invention. 18 and 19 are introduced to explain in more detail an organic Bragg grating plate 16 having a larger refractive index than the core layer 14 in the middle portion of the core layer 14.

Referring to FIG. 18, a lower clad layer 12a is formed on a 4 inch substrate 10, for example, a quartz substrate. The lower clad layer 12a is formed of a polymer film. The lower clad layer 12a is a low-loss polymer for thermal curing Exguide ZPU13-430 (ChemOptics Co., Ltd., a low-loss polymer having a refractive index of 1.430 μm to 1.430 μm) on the substrate 10, and then rotating the solution to a thickness of 13 μm. It is formed by thermal curing for 2 hours in a nitrogen atmosphere oven at 250 ℃.

The first core layer 13 is formed on the lower clad layer 12a. The first core layer 13 is rotated on the lower clad layer 12a so that a solution Exguide ZPU13-450 (a low loss polymer for thermosetting and a refractive index is 1.450 to 1.450 μm at an optical wavelength of 1.450 μm) on the lower clad layer 12a to have a thickness of 3.5 μm. After coating, it is formed by thermal curing for 2 hours in a nitrogen atmosphere oven at 250 ℃.

Next, drops of a brand name Exguide Co-152 (a low loss polymer for ultraviolet nanoimprint for ChemOptics, and a refractive index of 1.520 at a wavelength of 1.55 占 퐉) were prepared on a prefabricated silicon (Si) Bragg grating stamp (not shown). The substrate 10 having the first core layer 13 formed on the surface is turned over, pressed onto the silicon Bragg grating stamp, and then irradiated and cured with ultraviolet (UV) toward the substrate 10 to form the organic Bragg grating layer 15. Form. Subsequently, the silicon Bragg grating stamp and the substrate 10 are separated. Next, the brand name Exguide ZPU13-450 solution was spun on the organic Bragg grating plate 16 of the substrate 10 again to have a thickness of 3.5 μm, and then thermally cured in a nitrogen atmosphere oven at 250 ° C. for 2 hours. The core layer 17 is formed.

Referring to FIG. 19, the second core layer 17, the organic Bragg lattice layer 15, and the first core layer 13 may be formed using photolithography and O2 Reactive Ion Etching. The optical waveguide 18 composed of the upper core layer 14b, the organic Bragg grating plate 16, and the lower core layer 14a is formed by etching to a width of 7 mu m and a depth of 7 mu m. . The organic Bragg grating 16 is formed between the upper core layer 14b and the lower core layer 14a.

Next, the Exguide ZPU13-430 solution was spun on the substrate 10 on which the optical waveguide 18 was formed again to have a thickness of 13 μm, and thermally cured in a nitrogen atmosphere oven at 250 ° C. for 2 hours to form the upper clad layer 12b. Form. The column electrode 26 is formed on the upper clad layer 12b as needed.

As described above, the optical device of the present invention has an optical waveguide including an organic Bragg grating plate having a larger refractive index than the core layer in the middle portion of the core layer. Accordingly, the optical device of the present invention can propagate the optical waveguide with high reflectance and low loss.

In addition, the optical device of the present invention forms a column electrode on the optical waveguide, creates a tapered optical waveguide, or creates an organic Bragg grating plate having chirps in the center of the core layer of the optical waveguide. Filters and variable dispersion compensators can be implemented.

Claims (16)

A clad layer formed on the substrate, Consists of an optical waveguide formed in the cladding layer, The optical waveguide includes an core layer and an organic Bragg grating plate having a refractive index greater than that of the core layer and capable of reflecting or transmitting light having a specific wavelength in a middle portion of the core layer. The optical device of claim 1, wherein the core layer comprises a lower core layer and an upper core layer, and the organic Bragg grating plate is positioned between the upper core layer and the lower core layer. The optical device according to claim 1, wherein the thickness of the organic Bragg grating plate is 1/2 or less of the total thickness of the core layer. The optical device according to claim 1, wherein the organic Bragg grating plate comprises a residual layer and a rod or stick-shaped rod having a predetermined period on the residual layer. The optical device of claim 4, wherein a thickness of the residual layer is greater than zero and less than or equal to a thickness of the organic Bragg grating plate. A clad layer formed on the substrate, Consists of an optical waveguide formed in the cladding layer, The optical waveguide includes a lower core layer, an upper core layer, and an organic Bragg grating between the upper core layer and the lower core layer, having an index of refraction greater than that of the upper and lower core layers and capable of reflecting or transmitting light having a specific wavelength. Done, And a column electrode formed on the optical waveguide to be used as a variable wavelength filter and a variable dispersion compensator. The optical device according to claim 6, wherein the optical waveguide is a tapered optical waveguide having a width or a thickness varying along an optical axis. The optical device of claim 6, wherein the organic Bragg grating is a tapered organic Bragg grating having a width or thickness varying along an optical axis. 7. The device of claim 6, wherein the column electrode is a tapered column electrode whose width or thickness varies along the optical axis. The optical device of claim 6, wherein the organic Bragg grating is an organic Bragg grating having a constant bar cycle along the optical axis. 7. The optical device according to claim 6, wherein the organic Bragg grating is a lattice-shaped organic Bragg grating in which the bar period is changed along the optical axis. The optical device according to claim 6, wherein the optical waveguide is a tapered optical waveguide having a width or a thickness varying along an optical axis, and the organic Bragg grating is a tapered organic Bragg grating having a width or a thickness varying along the optical axis. The optical device according to claim 11 or 12, wherein the column electrode is a tapered column electrode whose width or thickness varies along an optical axis. The optical device of claim 6, wherein the organic Bragg grating plate is a tapered organic Bragg grating plate having a lattice shape in which a rod period is changed along an optical axis and a width or thickness thereof is changed along the optical axis. 15. The device of claim 14, wherein the optical waveguide is a tapered optical waveguide that varies in width or thickness along the optical axis. 15. The device of claim 14, wherein the column electrode is a tapered column electrode of varying width or thickness along an optical axis.

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